Kindlin-2, K2, is a peripheral membrane protein and co-activator of integrin signaling in the cell, which is implicated in cell migration, adhesion, and certain cancers. K2 contains a pleckstrin homology (PH) domain, which, like many PH domains, binds to the phosphoinositide components of the cell membrane, with highest affinity for phosphatidylinositol-3,4,5-trisphosphate (PIP3), to enhance integrin activation. However, the mechanism of PIP3 recognition and binding is not fully understood, as no structural studies to date use full-length PIP3 in lipid bilayers, focusing instead on the soluble inositol headgroup. In this study, we use a combination of solid-state and solution NMR to investigate the structure and dynamics of PIP3-bound K2-PH in a model membrane containing PIP3, phosphatidylcholine, phosphatidylserine, and cholesterol. We characterize the bound state, comparing it against unbound membranes and free protein to identify changes specific to binding. Our NMR results show chemical shift perturbations in the backbone of the bound protein compared to the unbound form, consistent with membrane-interacting regions predicted by MD simulations. Furthermore, the results indicate that additional membrane components, such as cholesterol, can stabilize the binding of the protein within the bilayer. Together, these results suggest that PIP3-binding induces structural changes in membrane-interacting regions of K2-PH, and that additional membrane components may help stabilize this interaction. Our findings help explain the mechanism of K2-PH binding to PIP3s in the context of a full-length lipid bilayer, which has broad implications for the PIP-based regulation of numerous important cellular processes.
Mustapha et al. (Sun,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: